The invention is directed to an extraction column for fissionable and/or breeder material, especially for the reprocessing of spent fuel elements with a pulsation mechanism.
The pulsation of the column thereby can be undertaken hydraulically and the addition of the extraction agent can be undertaken in the form of a dispersion in homogeneous distribution over the cross section of the column. The hydraulic fluid thereby is led over two sealing layers in such manner that normal pulsation pumps can be employed free from contamination, e.g. outside a hot cell.
In the nuclear art, especially in the reprocessing of spent fuel elements, the purification of uranium and plutonium is undertaken by liquid-liquid extraction in pulsated columns.
In order to avoid the installation of moving parts, such as pulsation pumps in hot cells, the columns are normally pulsated through air blasts (50 to 100 m.sup.3 /h), which in leaving drag along active aerosols. To eliminate the aerosols there are required expensive waste gas purification columns. Furthermore there are difficulties, particularly with large column diameters, in delivering the organic extraction agent solutions, e.g. 30% TBP (tributyl phosphate) and 70% dodecane which feed in at the bottom end of the column during the uniform pulsation over the cross section.
Additionally, all feeding places at the lower part of the column require welded supply pipes whose welding seams are more greatly stressed by corrosion and pulsation, than the smooth column parts and therefore form weak places in the construction of the columns.
Therefore, it was the problem of the present invention to develop an extraction column for fissionable and/or fertile materials, particularly for the reprocessing of spent fuel elements with a pulsation mechanism, in which no active aerosols form during the pulsation and in which in the lower part to the maximum extent possible there are needed no welded supply, withdrawal and pulsation connections, which by corrosion of the welded seams and/or stress crack formation due to the pulsation could represent a weak place in the column.